Virginia lawmakers are pressing Defense Secretary Leon Panetta to halt plans to move 4,900 Defense employees into the Mark Center facility in Alexandria, Va., by December — a move they say will clog local roads.

The 1.4 million-square-foot facility will house 6,400 employees by early next year, which northern Virginia lawmakers and traffic studies have said would lead to congestion and failing levels of service along local roads. DoD plans to start occupying the facility on Aug. 9.

Democratic Reps. Jim Moran, Gerry Connolly and Sens. Jim Webb and Mark Warner wrote the letter, saying the occupancy plan breaks the Defense Department's pledge to work with them to minimize the facility's impact.

The lawmakers asked the Defense Department to restrict itself to using 1,000 of the 3,800 parking spaces available at the Mark Center.

Moran had previously included the restriction in several bills, none of which have passed.

"It was our understanding that the department would delay to the longest extent possible the occupation of the Mark Center beyond what was statutorily required until sufficient transportation infrastructure was in place," the lawmakers wrote.

The new facility was one of the recommendations of the 2005 Base Realignment and Closure Commission.